Field of the Invention
The present invention relates to a wafer processing method for dividing a wafer into individual device chips along a plurality of crossing division lines, the front side of the wafer being partitioned by the division lines to define a plurality of separate regions where a plurality of devices corresponding to the device chips are formed, the front side of the wafer being previously covered with a cover plate.
Description of the Related Art
A plurality of devices such as integrated circuits (ICs), large-scale integrations (LSIs), charge-coupled devices (CCDs), and micro electro mechanical systems (MEMS) devices are formed on the front side of a wafer so as to be separated from each other by a plurality of division lines. The wafer thus having the devices on the front side is divided into individual device chips by a dicing apparatus having a cutting blade or by a laser processing apparatus for applying a laser beam. The device chips thus obtained are used in electrical equipment such as mobile phones, personal computers, digital cameras, and medical equipment.
Of these various devices, an image sensor including a CCD and MEMS devices are delicate devices, and it is known that if the front side of such a delicate device is soiled or scratched, the quality of the device is remarkably reduced. To cope with this problem, it has been proposed to provide a glass plate on the front side of a wafer having such devices, thereby protecting the front side of each device (see Japanese Patent Laid-open Nos. 2012-081551 and 2010-103327, for example).